1. Field of the Invention
The present invention is directed to an apparatus and method for determining blood glucose content by the collection and analysis of oral fluid.
2. Description of the Related Art
The pathogenesis of diabetes originates in sustained or periodic elevations of blood glucose and glucose in tissues secondary to a deficiency in, or insensitivity to, insulin. Glucose is linked non-enzymatically to accessible reactive sites of proteins causing altered structure and function which leads in time to diseased organs. The grade of glycation depends upon glucose concentration and the amount of derivitized protein accumulated depends upon the lifetime of the individual proteins effected. Accordingly, the significance of maintaining reduced glucose concentrations is widely accepted.
Although early studies focused on Type I diabetes patients (Cohen, 1988), it is generally believed that Type II diabetes individuals and others not taking insulin would benefit from better diabetic control. Although many patients tolerate the pin prick necessary for the taking of an actual blood sample, followed by blood analysis, a bloodless, quick and convenient test using saliva can enlist Type II individuals into an effective, better diabetic control. Type I persons would also benefit to the extent that a bloodless test would reduce the number of finger sticks required. The existence of a convenient, non-invasive test can also permit prescreening of a large number of individuals using the newly promulgated 126 mg/dL criteria.
Many prior art patents discuss the analysis of glucose in various fluids, including saliva, but do not discuss the relationship of determining blood glucose from saliva levels nor do they discuss any specific devices for obtaining the same. For example, U.S. Pat. No. 3,947,328 to Friedenberg et al., issued Mar. 30, 1976, discloses a method, apparatus and test compositions for a rapid, accurate test of concentration levels of various components of body fluids, including glucose levels in saliva. An oxidizing test is utilized to determine the levels, but no relationship is disclosed relating glucose analysis in saliva to blood levels of glucose. U.S. Pat. No. 5,139,023 to Stanley et al., issued Aug. 18, 1992, discloses a method and apparatus for non-invasive blood glucose monitoring. Blood glucose is monitored non-invasively by correlation with the amount of glucose which permeates an epithelial membrane, such as skin or a mucosa membrane within the mouth. However, the Stanley patent specifically states that it is undesirable for such a sample to be contaminated by oral fluid, specifically saliva. Although the Stanley et al. patent discloses the step of taking a sample from inside the mouth, the sample taken is not a sample of oral fluid or saliva.
U.S. Pat. No. 5,056,521 to Parsons et al., issued Oct. 15, 1991, discloses an absorbent non-reactive collecting swab which is brought into contact with a favorable surface of the oral cavity. An interstitial transudate is selectively collected from the vestibule region of the oral cavity at the conjunction of the superior labal mucous membrane and the superior gingivae between the upper canine teeth. The fluid collected is then squeezed out from the swab into a monitoring instrument located off site. The patent goes into great detail to note that, although general statements are made with regard to oral fluid, the system requires that the sample be taken from the specific mucous membrane described above so that the sample is devoid of uncontrolled oral fluid that might distort the glucose level in the sample by the diluting the desired fluid (namely, interstitial transudate, column 3, lines 35-40, of the Parsons et al. patent). From this sample, glucose levels of the sample itself are determined, the specification being devoid of any teaching of how blood levels of glucose can then be obtained. Hence, the Parsons et al. patent does not disclose any method or apparatus for utilizing whole oral fluid to determine blood glucose levels and, in fact, teaches away from using the same or from diluting a sample with such oral fluid.
In view of the above, it would be desirable to develop a non-invasive means for determining blood glucose levels. It is also desirable to provide a simple means for doing so which does not require exclusion of oral fluid from a bucual cavity device.